CVE-2019-9517: Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service

Published Aug 13, 2019
·
Updated

A vulnerability was found in http/2 where an attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both, potentially leading to a denial of service.

Other sources

A vulnerability was found in HTTP/2. An attacker can open a HTTP/2 window so the peer can send without constraint. The TCP window remains closed so the peer cannot write the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the server's queue is setup, the responses can consume excess memory, CPU, or both, potentially leading to a denial of service. The highest threat from this vulnerability is to system availability.

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

Affected Software

81 affected componentsFixes available
redhat/jbcs-httpd24-httpd<0:2.4.29-41.jbcs.el6
0:2.4.29-41.jbcs.el6
redhat/jbcs-httpd24-nghttp2<0:1.39.2-1.jbcs.el6
0:1.39.2-1.jbcs.el6
redhat/jbcs-httpd24-apr<0:1.6.3-63.jbcs.el6
0:1.6.3-63.jbcs.el6
redhat/jbcs-httpd24-apr-util<0:1.6.1-48.jbcs.el6
0:1.6.1-48.jbcs.el6
redhat/jbcs-httpd24-brotli<0:1.0.6-7.jbcs.el6
0:1.0.6-7.jbcs.el6
redhat/jbcs-httpd24-curl<0:7.64.1-14.jbcs.el6
0:7.64.1-14.jbcs.el6
redhat/jbcs-httpd24-httpd<0:2.4.37-33.jbcs.el6
0:2.4.37-33.jbcs.el6
redhat/jbcs-httpd24-jansson<0:2.11-20.jbcs.el6
0:2.11-20.jbcs.el6
redhat/jbcs-httpd24-nghttp2<0:1.39.2-4.jbcs.el6
0:1.39.2-4.jbcs.el6
redhat/jbcs-httpd24-openssl<1:1.1.1-25.jbcs.el6
1:1.1.1-25.jbcs.el6
redhat/jbcs-httpd24-httpd<0:2.4.29-41.jbcs.el7
0:2.4.29-41.jbcs.el7
redhat/jbcs-httpd24-nghttp2<0:1.39.2-1.jbcs.el7
0:1.39.2-1.jbcs.el7
redhat/jbcs-httpd24-apr<0:1.6.3-63.jbcs.el7
0:1.6.3-63.jbcs.el7
redhat/jbcs-httpd24-apr-util<0:1.6.1-48.jbcs.el7
0:1.6.1-48.jbcs.el7
redhat/jbcs-httpd24-brotli<0:1.0.6-7.jbcs.el7
0:1.0.6-7.jbcs.el7
redhat/jbcs-httpd24-curl<0:7.64.1-14.jbcs.el7
0:7.64.1-14.jbcs.el7
redhat/jbcs-httpd24-httpd<0:2.4.37-33.jbcs.el7
0:2.4.37-33.jbcs.el7
redhat/jbcs-httpd24-jansson<0:2.11-20.jbcs.el7
0:2.11-20.jbcs.el7
redhat/jbcs-httpd24-nghttp2<0:1.39.2-4.jbcs.el7
0:1.39.2-4.jbcs.el7
redhat/jbcs-httpd24-openssl<1:1.1.1-25.jbcs.el7
1:1.1.1-25.jbcs.el7
redhat/httpd24-httpd<0:2.4.34-8.el6.1
0:2.4.34-8.el6.1
redhat/httpd24-nghttp2<0:1.7.1-7.el6.1
0:1.7.1-7.el6.1
redhat/rh-nodejs10<0:3.2-3.el7
0:3.2-3.el7
redhat/rh-nodejs10-nodejs<0:10.16.3-3.el7
0:10.16.3-3.el7
redhat/httpd24-httpd<0:2.4.34-8.el7.1
0:2.4.34-8.el7.1
redhat/httpd24-nghttp2<0:1.7.1-7.el7.1
0:1.7.1-7.el7.1
redhat/rh-nodejs8<0:3.0-5.el7
0:3.0-5.el7
redhat/rh-nodejs8-nodejs<0:8.16.1-2.el7
0:8.16.1-2.el7
All of the following
Apple Swiftnio>=1.0.0<=1.4.0
Any of the following
Apple iOS and macOS>=10.12
Canonical Ubuntu Linux>=14.04
Apache HTTP Server>=2.4.20<2.4.40
Apache Traffic Server>=6.0.0<=6.2.3
Apache Traffic Server>=7.0.0<=7.1.6
Apache Traffic Server>=8.0.0<=8.0.3
Canonical Ubuntu Linux=16.04
Canonical Ubuntu Linux=18.04
Canonical Ubuntu Linux=19.04
Debian Debian Linux=9.0
Debian Debian Linux=10.0
Synology Skynas
Synology Diskstation Manager=6.2
All of the following
Synology Vs960hd Firmware
Synology Vs960hd
Fedoraproject Fedora=29
Fedoraproject Fedora=30
openSUSE Leap=15.0
openSUSE Leap=15.1
redhat JBoss Core Services=1.0
redhat JBoss Enterprise Application Platform=7.2.0
redhat JBoss Enterprise Application Platform=7.3.0
redhat Openshift Service Mesh=1.0
redhat Quay=3.0.0
redhat Software Collections=1.0
redhat Enterprise Linux=8.0
Oracle Communications Element Manager=8.0.0
Oracle Communications Element Manager=8.1.0
Oracle Communications Element Manager=8.1.1
Oracle Communications Element Manager=8.2.0
Oracle GraalVM=19.2.0
Oracle Instantis Enterprisetrack>=17.1<=17.3
Oracle Retail Xstore Point of Service=7.1
McAfee Web Gateway>=7.7.2.0<7.7.2.24
McAfee Web Gateway>=7.8.2.0<7.8.2.13
McAfee Web Gateway>=8.1.0<8.2.0
NetApp Clustered Data ONTAP
Nodejs Node.js>=8.0.0<=8.8.1
Nodejs Node.js>=8.9.0<8.16.1
Nodejs Node.js>=10.0.0<=10.12.0
Nodejs Node.js>=10.13.0<10.16.3
Nodejs Node.js>=12.0.0<12.8.1
Apple Swiftnio>=1.0.0<=1.4.0
Apple iOS and macOS>=10.12
Canonical Ubuntu Linux>=14.04
Synology Diskstation Manager=6.2
Synology Vs960hd Firmware
Synology Vs960hd
redhat/Nodejs<8.16.1
8.16.1
redhat/Nodejs<10.16.3
10.16.3
redhat/Nodejs<12.8.1
12.8.1
debian/apache2
2.4.62-1~deb11u12.4.66-1~deb11u12.4.66-1~deb12u12.4.62-1~deb12u22.4.66-1~deb13u22.4.66-8

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/jbcs-httpd24-httpd to a version that resolves this vulnerability.

    Fixed in 0:2.4.29-41.jbcs.el6
  2. Upgrade

    Upgrade redhat/jbcs-httpd24-nghttp2 to a version that resolves this vulnerability.

    Fixed in 0:1.39.2-1.jbcs.el6
  3. Upgrade

    Upgrade redhat/jbcs-httpd24-apr to a version that resolves this vulnerability.

    Fixed in 0:1.6.3-63.jbcs.el6
  4. Upgrade

    Upgrade redhat/jbcs-httpd24-apr-util to a version that resolves this vulnerability.

    Fixed in 0:1.6.1-48.jbcs.el6
  5. Upgrade

    Upgrade redhat/jbcs-httpd24-brotli to a version that resolves this vulnerability.

    Fixed in 0:1.0.6-7.jbcs.el6
  6. Upgrade

    Upgrade redhat/jbcs-httpd24-curl to a version that resolves this vulnerability.

    Fixed in 0:7.64.1-14.jbcs.el6
  7. Upgrade

    Upgrade redhat/jbcs-httpd24-httpd to a version that resolves this vulnerability.

    Fixed in 0:2.4.37-33.jbcs.el6
  8. Upgrade

    Upgrade redhat/jbcs-httpd24-jansson to a version that resolves this vulnerability.

    Fixed in 0:2.11-20.jbcs.el6
  9. Upgrade

    Upgrade redhat/jbcs-httpd24-nghttp2 to a version that resolves this vulnerability.

    Fixed in 0:1.39.2-4.jbcs.el6
  10. Upgrade

    Upgrade redhat/jbcs-httpd24-openssl to a version that resolves this vulnerability.

    Fixed in 1:1.1.1-25.jbcs.el6
  11. Upgrade

    Upgrade redhat/jbcs-httpd24-httpd to a version that resolves this vulnerability.

    Fixed in 0:2.4.29-41.jbcs.el7
  12. Upgrade

    Upgrade redhat/jbcs-httpd24-nghttp2 to a version that resolves this vulnerability.

    Fixed in 0:1.39.2-1.jbcs.el7
  13. Upgrade

    Upgrade redhat/jbcs-httpd24-apr to a version that resolves this vulnerability.

    Fixed in 0:1.6.3-63.jbcs.el7
  14. Upgrade

    Upgrade redhat/jbcs-httpd24-apr-util to a version that resolves this vulnerability.

    Fixed in 0:1.6.1-48.jbcs.el7
  15. Upgrade

    Upgrade redhat/jbcs-httpd24-brotli to a version that resolves this vulnerability.

    Fixed in 0:1.0.6-7.jbcs.el7
  16. Upgrade

    Upgrade redhat/jbcs-httpd24-curl to a version that resolves this vulnerability.

    Fixed in 0:7.64.1-14.jbcs.el7
  17. Upgrade

    Upgrade redhat/jbcs-httpd24-httpd to a version that resolves this vulnerability.

    Fixed in 0:2.4.37-33.jbcs.el7
  18. Upgrade

    Upgrade redhat/jbcs-httpd24-jansson to a version that resolves this vulnerability.

    Fixed in 0:2.11-20.jbcs.el7
  19. Upgrade

    Upgrade redhat/jbcs-httpd24-nghttp2 to a version that resolves this vulnerability.

    Fixed in 0:1.39.2-4.jbcs.el7
  20. Upgrade

    Upgrade redhat/jbcs-httpd24-openssl to a version that resolves this vulnerability.

    Fixed in 1:1.1.1-25.jbcs.el7
  21. Upgrade

    Upgrade redhat/httpd24-httpd to a version that resolves this vulnerability.

    Fixed in 0:2.4.34-8.el6.1
  22. Upgrade

    Upgrade redhat/httpd24-nghttp2 to a version that resolves this vulnerability.

    Fixed in 0:1.7.1-7.el6.1
  23. Upgrade

    Upgrade redhat/rh-nodejs10 to a version that resolves this vulnerability.

    Fixed in 0:3.2-3.el7
  24. Upgrade

    Upgrade redhat/rh-nodejs10-nodejs to a version that resolves this vulnerability.

    Fixed in 0:10.16.3-3.el7
  25. Upgrade

    Upgrade redhat/httpd24-httpd to a version that resolves this vulnerability.

    Fixed in 0:2.4.34-8.el7.1
  26. Upgrade

    Upgrade redhat/httpd24-nghttp2 to a version that resolves this vulnerability.

    Fixed in 0:1.7.1-7.el7.1
  27. Upgrade

    Upgrade redhat/rh-nodejs8 to a version that resolves this vulnerability.

    Fixed in 0:3.0-5.el7
  28. Upgrade

    Upgrade redhat/rh-nodejs8-nodejs to a version that resolves this vulnerability.

    Fixed in 0:8.16.1-2.el7
  29. Upgrade

    Upgrade debian/apache2 to a version that resolves this vulnerability.

    Fixed in 2.4.62-1~deb11u1Fixed in 2.4.66-1~deb11u1Fixed in 2.4.66-1~deb12u1Fixed in 2.4.62-1~deb12u2Fixed in 2.4.66-1~deb13u2Fixed in 2.4.66-8
  30. Upgrade

    Upgrade redhat/Nodejs to a version that resolves this vulnerability.

    Fixed in 8.16.1
  31. Upgrade

    Upgrade redhat/Nodejs to a version that resolves this vulnerability.

    Fixed in 10.16.3
  32. Upgrade

    Upgrade redhat/Nodejs to a version that resolves this vulnerability.

    Fixed in 12.8.1
  33. Configuration

    Remove HTTP/2 protocol support by deleting the 'h2' and 'h2c' tokens from the HTTP/2-related configuration lines using: sed -i 's/\(h2\)\|\(h2c\)//g' <httpd_config_file>.

    Apache httpd (HTTP/2 via mod_http2) HTTP/2 protocol support in httpd configuration = disable
  34. Compensating control

    Disable HTTP/2 support as mitigation (since the mod_http2 package is not updated) and ensure HTTP/2 is not enabled in the server configuration.

  35. Operational

    Stop and restart the Apache httpd service after configuration changes: run systemctl stop httpd, then systemctl start httpd.

  36. Operational

    Validate the updated configuration syntax before/after changes by running apachectl configtest.

Event History

Aug 13, 2019
CVE Published
12:00 AM
CVE Published
via MITRE·08:50 PM
Data Sourced
via MITRE·08:50 PM
DescriptionSeverityWeakness
Aug 16, 2019
Data Sourced
via Red Hat·09:57 AM
DescriptionSeverityAffected Software
Feb 20, 2026
Data Sourced
via Ubuntu·09:34 PM
RemedyDescriptionSeverityAffected Software
Data Sourced
via Launchpad·09:35 PM
Description
Mar 14, 2026
Data Sourced
via Debian·09:53 PM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is the vulnerability ID?

The vulnerability ID is CVE-2019-9517.

2

What is the severity of CVE-2019-9517?

The severity of CVE-2019-9517 is high.

3

What is affected by CVE-2019-9517?

HTTP/2 implementations such as Nodejs (versions 8.16.1, 10.16.3, 12.8.1) and jbcs-httpd24-* (various versions) are affected by CVE-2019-9517.

4

How can I fix CVE-2019-9517?

To fix CVE-2019-9517, you should update your affected software to the recommended versions provided by the vendor.

5

Where can I find more information about CVE-2019-9517?

You can find more information about CVE-2019-9517 on the Red Hat Bugzilla website.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203